Vulcanization accelerators



Patented May 4, 1943 UNITED STATES TENT opener:

VULCANIZATION ACCELERATORS Roy S. Hanslick, Nashville, Tenn, assignor to United States Rubber Company, New York, N; Y., a corporation of New Jersey N Drawing. Original application June 22, 1939, Serial No. 280.445. Divided and this application May; 9 1940, Serial No. 334,174

Claims.

This invention relates to a new class of compounds which have been foundvaluable. as accelerators of the vulcanization of rubberand particularly as activators of accelerators of: the mercaptobenzothiazole class.

This case is a division of my copending application Serial No. 280,445, filed June 22, 1939.

The new class of rubber vulcanization accelerators are the reaction products of compounds containing the group The following examples are given to illustrate the invention:

Example I A water solution containing 42.9 grams (0.3 mole) of sodium dimethyl dithiocarbamate is cooled to 05 C. by means of an ice-water bath. A freshly prepared water solution containing 15.5 grams (0.3 mole) plus 10% excess of monochloramine chilled to 0-5 0., is slowly added to the aqueous sodium dimethyl dithiocarbamate solution. Rapid stirring is employed. Upon the complete addition of the aqueous monochloramine solution, stirring is continued for five to ten minutes whereupon the white material is then filtered off and washed with water. The material is then dried. Melting point is IO-71 C. (uncorrected) Dimethyl thiocarbamyl sulfamine is obtained in a yield of 39-405 grams.

The reaction may be expressed as follows:

on: s

N-C S Na+l\ H201 C H; Sv

ANALYSIS Theory Obtained Per cent Per cent Nitrogen 20. 4 20. 2 Sulfur 45. 6 46. 1

Example II A water solution containing 22.7 grams (0.1 mole) of sodium di-n-butyl dithiocarbamate is cooled to 0-5 C. 5.15 grams (0.1 mole) plus 10% excess of monochloramine in aqueous solution is added with good stirring of the mixture solution. A white precipitate is formed which is filtered olT, washed with water and then dried. The material is low melting. Di-n-butyl thiocarbamyl sulfamine is obtained in a yield of 20-21.5 grams.

Example III A water solution containing 31.1 grams (0.1 mole) of potassium dibenzyl dithiocarbamate is cooled to 0-5 C. A freshly prepared solution of 5.15 grams (0.1 mole) plus 10% excess of monochloramine in aqueous solution is added to the potassium dithiocarbamate solution. A precipitate separates and the solution is well stirred. The material is filtered off, washed with water and then dried. Melting point is 6669 C. (un- Similarly compounds such as oxy-di-ethylene thiocarbamyl sulfamine (melting point 126-128 C. (uncorrected)) and cycle penta methylene thiocarbamyl sulfamine (melting point 43-44 C. (uncorrected)) may be prepared.

Instead of sodium or potassium salts of dithiocarbamic acids, there may be used the ammonium, calcium, barium, and other metal salts for reaction with chloramine.

The dithiocarbamate employed to react with monochloramine may be N-substituted with various groupings such as ethyl, propyl, isopropyl, isobutyl, amyl, isoamyl, phenyl, cyclohexyl, phenyl ethyl, heterocyclic radicals from morpholine, and piperidyl, such as cyclopentamethylene and oxy-di-ethylene.

In the preferred compounds, namely the dialkyl substituted dithiocarbamates, which are used to react with monochloramine, the alkyl groups may be any of the above referred to alkyl groups, and the alkyl groups may be similar or dissimilar in any given compound, to produce the corresponding dialkyl thiocarbamyl sulfamines.

The following data illustrates'the accelerating effect of the compounds; the parts are by weight:

. Re ipe Pale crepe 100 Zinc oxide Whiting 60 Lithopone 60 Zinc soap of cocoanut oil acids 0.50 Sulfur 3.00 Zinc salt of mercaptobenzothiazole 0.50

. Master batch 229.00 Dimethyl thio carbamyl sulfamine 0.05

Tensiles UNAGED Cure in minutes at lbs/sq. in. steam T E pressure 1 1500 640 2560 680 2000 ess 2000 ass T=ultimate tensiles in pounds per square inch.

E=percent elongation at break.

If desired, the new accelerators may be used with any of the well-known basic nitrogen-containing accelerators used in activating the accelerators of the mercapto thiazole type, including the guanidine and substituted guanidine salts, such as diphenyl guanidine salt of aliphatic and aromatic acids.

The present accelerators are best used in con junction with arylene thiazyl sulphide acce1er ators such as mercaptobenzothiazole and its derivatives, including its salts, such as those of zinc. In this connection the two accelerators may be added separately on the mill or they may be mixed prior to addition on the mill.

The term rubber herein is to be understood as including caoutchouc, and similar vulcanizable gums, natural or synthetic, including latices thereof.

The present invention is not limited to the specific examples above set forth wherein the preferredaccelerator is employed. Other ratios of the compounding ingredients than those mentioned in the examples as well as other well known fillers, pigments and the like may be employed in the production of various types of rubber compounds as will be apparent to those skilled in the art to which this invention pertains.

Having thus described my invention, what I claim and desire to protect by Letters Patent is 1. As a new compound, an N-substituted thiocarbamyl sulfamine having the formula in which R and R1 are aliphatic hydrocarbon groups.

2. As a new compound, an N -dialkyl thiocarbamyl sulfamine in which the amine group is represented by -NH2.

3. As a new compound, an N-dimethyl thiocarbamyl sulfamine in which the amine group is represented by --NH2.

l 4. As a new compound, an N-dibutyl thiocarbamyl sulfamine in which the amine group is represented by NH2.

5. As a new compound, an N-dibenzyl thiocarbamyl sulfamine in which the amine group is represented by --NH2.

' ROY S. HANSLICK. 

